The present invention relates to a torque transmission arrangement, and more particularly, to an arrangement for the influenceable transmission of torques between machine elements, particularly for transmitting braking or drive torques from or to a drive shaft of a press, having a first, rotatably disposed element and having a second element between which friction devices are arranged which can be engaged and disengaged in a controlled manner and to which a selectively controllable operating device is assigned, and having a cooling device which has a duct leading to the friction device for feeding a fluid coolant to the friction device as well as a space for removing the coolant from the friction device. The arrangement is used, for example, to non-rotatable couple machine elements with one another as necessary. In particular, the arrangement is provided as a braking and clutch device on mechanical presses, such as vehicle body presses for controlling the power flux from and to the plunger of the press.
Vehicle body presses are eccentric presses in which the eccentric is usually driven by way of a step-down gear whose input or drive shaft is connected with a drive source by a braking and clutch device. The drive source rotates continuously. A flywheel is provided on the drive source for the load buffering.
The braking and clutch device is a frictional clutch with friction elements which rub against one another during clutch engagement. The friction results in a rotational speed adaptation of the machine elements to be coupled and thus in their acceleration and/or deceleration, such that the friction elements heat up. Because of the frequent and regular acceleration and braking operations in vehicle body presses, a considerable power is converted so that the friction elements must be cooled.
DE 28 00 838 C2 describes a friction clutch and brake combination for presses which uses an open cooling circulating system. This arrangement has two multi-plate bundles which are disposed on a rotatably disposed shaft and which each contain a multi-plate group which is non-rotatably but axially displaceably coupled with the shaft. While one multi-plate bundle has a group of plates which a non-rotatably held on the outer circumference side, plates of the other multi-plate bundle are non-rotatably connected on the outer circumference side with a flywheel. A pneumatic cylinder of a large diameter and a very short length which is coaxial with respect to the shaft and resiliently prestressed is used for the operation.
A coolant duct which is arranged coaxially in the shaft and branches into ducts which extend radially to the outside in the area of the multi-plate bundles is provided for the cooling of the plates. These ducts are fanned out again and lead in each case by way of several outlet bores into the inner circumference area of the multi-plate bundles. For collecting the coolant thrown to the outside by the circulating braking and clutch arrangement by centrifugal force, a ring-shaped housing circulates with the flywheel and has mutually opposite front sides on which collecting bowls are provided for the removal of the thrown-out coolant.
DE 43 42 163 A1 describes a braking and clutch arrangement with two plate brakes for shifting a planetary transmission. The first brake called a multi-plate clutch transmits, as required, the supporting moment of the ring gear of the planetary transmission to a transmission case. The other multi-plate bundle called a multi-plate brake is used for coupling the planet carrier to the transmission case. The non-rotatably disposed plates are connected on their outer circumference side with the transmission case. The other multi-plate bundles are disposed on their inner circumference side on hollow shaft plate carriers. For the alternating operation of the plate brake, a non-rotating ring pistons is arranged between the multi-plate bundles and is axially movable by a pressure medium. For cooling the multi-plate clutch (brake), the housing has a ring-shaped water jacket. In addition, the plate carriers are provided with radial bores for transporting cooling oil through the multi-plate bundles in the radial direction from the inside to the outside.
U.S. Pat. No. 3,860,100 discloses a braking and clutch device. Two multi-plate bundles selectively connect a shaft with a housing or with a gear wheel which meshes with a drive shaft pinion. A ring-shaped piston, which is disposed in a ring-shaped recess of the housing which opens axially to one side and is arranged coaxially to the output shaft, is used as the operating device. The piston operates one of the multi-plate bundles by way of a tapered roller bearing. In all the above-mentioned conventional arrangements, however, the capacity to be stressed is limited by the heat development.
It is an object of the present invention to provide an arrangement for an influenceable torque transmission which has a high efficiency while its space requirements are low.
This object has been achieved in accordance with the present invention by fixing the flow direction and the guiding of coolant to extend through the multi-plate bundle from the outside to the inside, i.e., against the effect of the centrifugal force. Thereby, still cold coolant first arrives at the areas of the multi-plate bundles which are on the outside in the radial direction, where the highest speed difference and the largest power conversion occur. The increased cooling of the critical outside areas increases the efficiency, i.e., the achievable power dissipation of the arrangement.
Furthermore, as the result of the guiding of the coolant from the outside to the inside in accordance with the present invention, a low coolant pressure is achieved in the interior of the arrangement which facilitates the sealing between the shaft and the housing.
Preferably, the duct leading to the friction device and the duct leading away from the friction device form a cooling system which is statically sealed off to the outside and dynamically sealed off to the inside. The sealing-off of the cooling system against increased interior pressure takes place by a construction of the cooling-medium-carrying spaces which is closed to the outside, without the use of labyrinth seals, collecting bowls or rings for catching thrown-off oil. Slipping seals, such as lip seals or the like, are used as seals between moved parts. As a result, a simple and space-saving construction is achieved and the manufacturing costs are lowered.
Also, the present invention avoids sealing problems which would be the result of the use of no-contact seals because of the high required cooling oil flows. Thus, coolant flows which are naturally larger than oil flows, as used, for example, for the bearing of machine elements can be securely guided.
With the closed construction of the cooling system and the use of slipping seals of the present invention, the coolant can be transported through the multi-plate bundles (friction devices) at an increased pressure. This and the improved sealing permits the increase of the coolant flows, of the cooling effect and thus of the efficiency.
Advantageously, the brake and clutch elements (clutch halves) define a housing whose interior is filled with coolant (e.g., oil) preferably without any bubbles. An increase of the shearing work, i.e., dissipated power of the clutch, which occurs as a result of the oil filling, can be accepted, after we found that the complete filling of the housing with coolant effectively counteracts a foam formation and improves the cooling effect.
The cooling system of the present invention has a central coolant feeding by way of a coaxial connection piece. The connection piece has coolant ducts and, as needed, a pressure medium duct for the operating device whereby the guiding of coolant in a closed circulation and in any direction as well as with a hydraulic excess pressure is permitted.
The arrangement is preferably constructed as an outside-closing system. As a result, the operating device is connected with the outside element (the clutch half) which is operationally subjected to lower rotational accelerations or decelerations. During the pressing, this is the clutch half which is connected with the flywheel and which preferably has a plate carrier which is situated radially on the outside with respect to the multi-plate bundles. The mass moment of inertia of the drive shaft to be accelerated and braked is reduced to a minimum. Correspondingly, the dissipated power is reduced which occurs during the coupling with the flywheel. This arrangement permits a reduction of the required space or an increase of the power or torques to be transmitted. Because of an interposed step-down gear, mass moments of inertia of other elements, such as the eccentric drive, the slide, etc. have less influence.
A hydraulic operating device offers a fast response behavior and a high force development while the space requirements and weight are low.